This invention relates to a radio antenna of either mobile or fixed station which provides a remote control of a tuning frequency that the antenna receives or transmits.
These days, the number of cars which are equipped with radio systems has remarkably increased. Those systems available for amateur radio operators have particularly increased in number and accordingly the radio technique in the amateur radio field has shown a remarkable progress such that the radio system has become compact and shown improved performance. Eventually this improvement has led to the advent of a radio system, which has a number of bands, yet can be mounted onto a vehicle.
In view of the above situation an improvement also has been requested in view of antenna which preferably can cover a number of bands with a single antenna element thereof.
The following types of antennas have been popularly used as antennas which can cover a number of bands:
(a) a whip-type antenna which is provided with replaceable inductance coil at the middle thereof, PA1 (b) a whip-type antenna having a variable inductance coil at the middle thereof wherein inductance of the coil is variable manually or by a power-operated motor, and PA1 (c) a whip-type antenna having three kinds of inductance coils at the middle of the whip antenna.
However, these antennas are less than optimal in their performance and appearance due to the constructional restriction set forth above. Namely, in view of the performance of above whip-type antennas, the variation of inductance which corresponds to the variation of tuning frequency has been conducted either by the replacement of the inductance coil or the inductance variation of the short coil attached to the middle of the antenna so that the tuning frequency that such antennas can cover is defined to a limited range and the replacing operation is cumbersome.
Accordingly, it is an object of the present invention to provide a whip-type antenna which can vary the tuning frequency in a wide range overcoming the defects of conventional whip-type antenna.
It is another object of the present invention to provide a whip-type antenna which is characterized in that the tuning frequency of the whip antenna is varied corresponding to the variation of turns or pitch of loading (inductance) coils which is conducted by a power-operated motor.
Although the invention is illustrated and described in relationship to specific embodiments, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and operation of the invention, however, together with additional objects and advantages, thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.